Two-diameter thread rolling device



28, 19 H. F. SEIBERT 2,760,388

TWO-DIAMETER THREAD ROLLING DEVICE Filed May 18, 1953 2 Sheets-Sheet 1 I INVENTOR m Howm-dF ATTORNEY 28, 1956 I H. F. SEIBERT 2,760,388

TWO-DIAMETER THREAD ROLLING DEVICE Filed May 18, 1953 2 Sheets-Sheet 2 INVENTOR 170 wardli'seiber.

ATTORNEY United States Patent TWO-DIAMETER THREAD ROLLING DEVICE Howard F. Seibert, Lebanon, Pa., assignor to Bethlehem Steel Company, a corporation of Pennsylvania Application May 18, 1953, Serial No. 355,440

2 Claims. (Cl. 80-9) My invention relates in general to improvements in thread-rolling devices of the reciprocating die type, and more particularly to improvements in the dies between which the workpiece is rolled.

In thread-rolling devices of the subject type, the cylindrical blank workpiece is rolled between pairs of reciprocating grooved dies which squeeze the desired threads thereon. This is a quite satisfactory method of forming the threads of ordinary bolts and screws, but the rolling of threads and/or ribs or knurling on .bodies having two or more different diameters presents special difliculties. In the latter case, with each rotation of the workpiece, its larger diameter moves at a greater surface speed than its smaller diameter. The working surfaces of the usual dies being in fixed relation to each other on each side, the varying peripheral speeds on the workpiece will cause undue twisting and slippage of the workpiece and excessive and uneven wear on the dies.

A typical two-diameter article which is suitable to be rolled by means of the present invention is a structural rib bolt, which has a ribbed neck adapted to be driven tightly into a hole in a member to provide a tight grip, and also has a smaller end threads of any standard profile. However, the invention may also be applied to rolling carriage bolts with ribbed necks, and to other special types of multi-diameter cylindrical metal bodies.

One object of this invention, therefore, is the provision of means for rolling perfect threads and/or ribs or knurling of two or more different neutral diameters on a workpiece at the same time.

Another object is the provision of reciprocating straight dies in sections which are self-adjusting. longitudinally to compensate for difierences in the diameters of separate zones on the workpiece.

Still other and further objects, purposes, and advantages of the invention will appear herein after in the specification and claims, and in the annexed two sheets of drawings.

In the drawings:

Figs. 1, 2, 3 and 4 are top plan views of the dies and workpiece in successive stages of the thread-rolling operation;

Fig. 5 is a fragmentary detail section of one end of a movable die in its die-holder, with support pin and return spring; a

Fig. 6 is an end elevation of the dies rolling a workpiece;

Fig. 7 is a horizontal section of the movable die and die-holder; and

Fig. 8 is a side elevation showing the Working faces of the dies.

Referring in detail to the drawings, the workpiece shown is a headed round blank 1 upon which threads 2 are to be rolled upon its lower portion and ribs 3 upon ice 'the inner =faceszof .the identical dieblocks .4 is suitably.

recessed to receive a lower stationary thread-rolling die 5, which may be of any standard type, and a removable upper die-holder 6. Each die-holder 6 is longitudinally recessed as at 7 and provided with integral side fingers 8 to retain a movable ribbing die 9 having portions cut away at each end as at 10 and being somewhat shorter than the die-holder recess 7 in which it is slidably seated. Shouldered holes 11 positioned in longitudinal alignment at each end of the movable die 9 receive return springs 12 and guide pins 13 inserted in complementary holes 14 in the die-holder 6. Said holes 14 are also provided with screw plugs 15 and 16 in their outer ends, and bolts 17 and hold-down plate 18 clamp each assembly together.

The working faces of both the thread-rolling dies 5 and the rib-rolling dies 9 will project outwardly from the inside faces of the die-blocks 4 as in Fig. 6, but the dies 5 being required to roll the smaller diameter of the blank must be set out somewhat further than the dies 9. The blank may be worked either hot or cold, the latter condition being usually preferred for forming the smaller sizes of product.

Figs. 1 to 4 inclusive show the sequence of operations in forming the bolt. In Fig. 1 the blank 1 is shown as tion, with the floating ribbing dies 9 in their normal center position. Rolling is continued as the moving die advances until the blank 1 reaches the position shown in Fig. 2, wherein the blank has contacted the floating ribbing dies 9, forced them against the solid backing of their respective die-holders 6, and has begun the rolling of the ribs 3. Fig. 3 shows the continuation of combination ribbing and thread-rolling and illustrates the manner in which the floating ribbing dies 9 move to compensate for the variations in surface speed of the two diameters of the bolt. In Fig. 4, the rolling is shown as completed, With the finished product at the discharge position and ready to drop out of the machine, and the floating ribbing dies 9 returned to their original position.

It will be understood, of course, that the thickness of each fixed lower die 5 and the combined thickness of the upper die 9 and the die-holder 6, as well as the individual configuration of each die, may be varied to roll cylindrical metal articles of many difierent types and sizes. Also, it is evident that a plurality of superposed movable dies and die-holders may be combined with a fixed die so as to roll articles of more than two diameters in substantially the same manner as above described.

Although I have thus described my invention hereinabove and in considerable detail, I do not wish to be limited narrowly to the exactand specific structure shown,

but I may also use such modifications, substitutions, or

die-holding member, a second die longitudinally mOV-e.

able on said guide members, and resilient means attached between said second die and said die-holding member tending to resist the longitudinal motion of said second die during the shaping of the blanks.

" m, the die block beneath the rib=rol1ing die; 10.

I a yeonss A device fonribbingand'threading'a'two-dianieter References Cited in tlie file of this patent metalblanklwmpri in amt 9i spec/ed 1 ,l.'QQbl.-. die. .7 I WEBB STATES. E

blocks, each of said die blocks having a recess in its in- V ner face, a removable die holder secured in said recess 408,529 Rodgers -r- Aug-5,1389 and having a longitudinal opening, guide pins at each end 5' 470,805 Jones 1892 of the die holder and projecting into said opening, a rib- 7 7 Ric ards Mar. 17, 1942 s rolling' die longitudinally slidgble on said guide pins, re- FOREIGN PATENTS turn springs normally centering said rib-rolling die in the die-holder opening, and a thread rolling die fi xed 435,304 Great Britain Sept. 18, 1935 s 

